Intramedullary (IM) nailing or fixation has enjoyed a tremendous amount of clinical success over the last 40 years. Modern IM nailing as it is known today began during World War II with the work of Gerhard Kuntscher in Germany. Kuntscher's nail and method worked for primarily two reasons. First, the hardware provided stable fixation allowing early mobilization of the patient while the fracture had time to heal. Secondly, the method was that of closed nailing with the incision and point of entry into the femoral canal far removed from the actual fracture site.
This closed method limits the damage to soft tissues and blood supply overlying the fracture and hence greatly reduces the risk of infection and/or possible nonunion. Kuntscher's original method is however limited in that it does not rigidly hold a fracture in the proximal or distal regions of the femoral shaft. The reason for this is that Kuntscher's nail has a constant cross section. Unfortunately the endosteal canal of the femur (for that matter of all long bones) is a constant cross section over a limited length-typically the middle one-third of the shaft. The endosteal canal enlarges or expands in the proximal one-third of the shaft and particularly the distal one-third regions of all long bones.
In an attempt to solve this problem in the case of the femur a number of IM devices have evolved over the years. The current state of the art with regards to IM fixation of these proximal and distal femur fractures is such that it is handled by a number of different methods. Some inventors have designed a specific device to internally fix a specific fracture pattern. Zickel designed a subtrochanteric nail (U.S. Pat. No. 3,433,220) for the fixation of subtrochanteric fractures as well as a supracondylar nail (U.S. Pat. No. 4,011,863) for the fixation of supracondylar fractures. Fischer, et al. (U.S. Pat. Nos. 3,759,257; 3,760,802; 3,799,239) all are primarily directed at fixation of fractures in the metaphyseal region of long bones. Aginsky (U.S. Pat. Nos. 4,091,806 and 4,227,518) discloses at least in part some of the problems associated with proximal and distal fixation without employing any interlocking principle. The interlocking principle has been applied to these fracture patterns over the last decade. It involves the use of an IM rod which contains holes proximally and distally through which transfixion screws are inserted in order to obtain stability of proximal and/or distal fracture patterns as well as fractures involving the middle one-third of the shaft. Examples here being the Klemm-Schellmann, Grosse-Kempf, Russel-Taylor, Williams (U.S. Pat. No. 4,697,585) and the Brooker-Wills (U.S. Pat. No. 4,519,100) systems. Finally, multiple Ender pins (U.S. Pat. No. 4,169,470) which are a classic example of flexible pinning is being used more frequently for fixation of shaft and distal femoral fractures using a method known as "bundle nailing".
While many of the above-mentioned devices have been beneficial in the treatment of various fracture patterns, they have some distinct disadvantages. Some of the "specific devices" mentioned are so specific that they are only beneficial in the treatment of a specific fracture pattern and not to other fractures involving the shaft of a long bone. Others are complicated mechanically having several moving parts which may or may not work in an "in vivo" environment. Still others fail to appreciate lessons learned from authorities like Frederic Rhinelander on the vascular response of bone to internal fixation. The interlocking nails are popular but have some definite disadvantages. For example, the problems of distal screw fixation, as yet unsolved, are that they cannot be easily instrumentated, require significant teaching of the technique which involves additional radiation exposure to the surgical team, and lastly, inherently weaken the IM portion of the device.